/* exechelp-w32.c - Fork and exec helpers for W32CE.
 * Copyright (C) 2004, 2007, 2008, 2009,
 *               2010 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

#if !defined(HAVE_W32_SYSTEM) && !defined (HAVE_W32CE_SYSTEM)
#error This code is only used on W32CE.
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#ifdef HAVE_SIGNAL_H
# include <signal.h>
#endif
#include <unistd.h> 
#include <fcntl.h>

#ifdef WITHOUT_GNU_PTH /* Give the Makefile a chance to build without Pth.  */
#undef HAVE_PTH
#undef USE_GNU_PTH
#endif

#ifdef USE_GNU_PTH      
#include <pth.h>
#endif

#ifdef HAVE_STAT
# include <sys/stat.h>
#endif

#include <assuan.h>

#include "util.h"
#include "i18n.h"
#include "sysutils.h"
#include "exechelp.h"


/* It seems Vista doesn't grok X_OK and so fails access() tests.
   Previous versions interpreted X_OK as F_OK anyway, so we'll just
   use F_OK directly. */
#undef X_OK
#define X_OK F_OK


/* We assume that a HANDLE can be represented by an int which should
   be true for all i386 systems (HANDLE is defined as void *) and
   these are the only systems for which Windows is available.  Further
   we assume that -1 denotes an invalid handle.  */
#define fd_to_handle(a)  ((HANDLE)(a))
#define handle_to_fd(a)  ((int)(a))
#define pid_to_handle(a) ((HANDLE)(a))
#define handle_to_pid(a) ((int)(a))


#ifdef USE_GNU_PTH      
/* The data passed to the feeder_thread.  */ 
struct feeder_thread_parms
{
  estream_t stream;
  int fd;
  int direction;
};


/* The thread started by start_feeded.  */
static void *
feeder_thread (void *arg)
{
  struct feeder_thread_parms *parm = arg;
  char buffer[4096];

  if (parm->direction)
    {
      size_t nread;
      DWORD nwritten;

      while (!es_read (parm->stream, buffer, sizeof buffer, &nread))
        {
          do
            {
              if (!WriteFile (fd_to_handle (parm->fd), 
                              buffer, nread, &nwritten, NULL))
                {
                  log_debug ("feeder(%d): WriteFile error: rc=%d\n",
                             parm->fd, (int)GetLastError ());
                  goto leave;
                }
              nread -= nwritten;
            }
          while (nread);
        }
      if (nread)
        log_debug ("feeder(%d): es_read error: %s\n",
                   parm->fd, strerror (errno));
    }
  else
    {
      DWORD nread;
      size_t nwritten;

      while (ReadFile (fd_to_handle (parm->fd),
                       buffer, sizeof buffer, &nread, NULL) && nread)
        {
          do 
            {
              if (es_write (parm->stream, buffer, nread, &nwritten))
                {
                  log_debug ("feeder(%d): es_write error: %s\n",
                             parm->fd, strerror (errno));
                  goto leave;
                }
              nread -= nwritten;
            }
          while (nread);
        }
      if (nread)
        log_debug ("feeder(%d): ReadFile error: rc=%d\n",
                   parm->fd, (int)GetLastError ());
      else
        log_debug ("feeder(%d): eof\n", parm->fd);
    }

leave:
  CloseHandle (fd_to_handle (parm->fd));
  xfree (parm);
  return NULL;
}
#endif /*USE_GNU_PTH*/

/* Fire up a thread to copy data between STREAM and a pipe's
   descriptor FD.  With DIRECTION set to true the copy takes place
   from the stream to the pipe, otherwise from the pipe to the
   stream.  */
static gpg_error_t
start_feeder (estream_t stream, int fd, int direction)
{
#ifdef USE_GNU_PTH      
  gpg_error_t err;
  struct feeder_thread_parms *parm;
  pth_attr_t tattr;
  
  parm = xtrymalloc (sizeof *parm);
  if (!parm)
    return gpg_error_from_syserror ();
  parm->stream = stream;
  parm->fd = fd;
  parm->direction = direction;
  
  tattr = pth_attr_new ();
  pth_attr_set (tattr, PTH_ATTR_JOINABLE, 0);
  pth_attr_set (tattr, PTH_ATTR_STACK_SIZE, 64*1024);
  pth_attr_set (tattr, PTH_ATTR_NAME, "exec-feeder");
  
  log_error ("spawning new feeder(%p, %d, %d)\n", stream, fd, direction);
  if(!pth_spawn (tattr, feeder_thread, parm))
    {
      err = gpg_error_from_syserror ();
      log_error ("error spawning feeder: %s\n", gpg_strerror (err));
      xfree (parm);
    }
  else
    err = 0;
  pth_attr_destroy (tattr);

  return err;
#else
  (void)stream;
  (void)fd;
  (void)direction;
  return gpg_error (GPG_ERR_NOT_IMPLEMENTED);  /* No Pth.  */
#endif
}



/* Return the maximum number of currently allowed open file
   descriptors.  Only useful on POSIX systems but returns a value on
   other systems too.  */
int
get_max_fds (void)
{
  int max_fds = -1;

#ifdef OPEN_MAX
  if (max_fds == -1)
    max_fds = OPEN_MAX;
#endif

  if (max_fds == -1)
    max_fds = 256;  /* Arbitrary limit.  */

  return max_fds;
}


/* Close all file descriptors starting with descriptor FIRST.  If
   EXCEPT is not NULL, it is expected to be a list of file descriptors
   which shall not be closed.  This list shall be sorted in ascending
   order with the end marked by -1.  */
void
close_all_fds (int first, int *except)
{
  int max_fd = get_max_fds ();
  int fd, i, except_start;

  if (except)
    {
      except_start = 0;
      for (fd=first; fd < max_fd; fd++)
        {
          for (i=except_start; except[i] != -1; i++)
            {
              if (except[i] == fd)
                {
                  /* If we found the descriptor in the exception list
                     we can start the next compare run at the next
                     index because the exception list is ordered.  */
                except_start = i + 1;
                break;
                }
            }
          if (except[i] == -1)
            close (fd);
        }
    }
  else
    {
      for (fd=first; fd < max_fd; fd++)
        close (fd);
    }

  gpg_err_set_errno (0);
}


/* Returns an array with all currently open file descriptors.  The end
   of the array is marked by -1.  The caller needs to release this
   array using the *standard free* and not with xfree.  This allow the
   use of this fucntion right at startup even before libgcrypt has
   been initialized.  Returns NULL on error and sets ERRNO
   accordingly.  */
int *
get_all_open_fds (void)
{
  int *array;
  size_t narray;
  int fd, max_fd, idx;
#ifndef HAVE_STAT
  array = calloc (1, sizeof *array);
  if (array)
    array[0] = -1;
#else /*HAVE_STAT*/
  struct stat statbuf;

  max_fd = get_max_fds ();
  narray = 32;  /* If you change this change also t-exechelp.c.  */
  array = calloc (narray, sizeof *array);
  if (!array)
    return NULL;
  
  /* Note:  The list we return is ordered.  */
  for (idx=0, fd=0; fd < max_fd; fd++)
    if (!(fstat (fd, &statbuf) == -1 && errno == EBADF))
      {
        if (idx+1 >= narray)
          {
            int *tmp;

            narray += (narray < 256)? 32:256;
            tmp = realloc (array, narray * sizeof *array);
            if (!tmp)
              {
                free (array);
                return NULL;
              }
            array = tmp;
          }
        array[idx++] = fd;
      }
  array[idx] = -1;
#endif /*HAVE_STAT*/
  return array;
}



static char *
copy_quoted (char *p, const char *string)
{
  const char *s;

  if (!*string) /* Empty string. */
    p = stpcpy (p, "\"\"");
  else if (strpbrk (string, " \t\n\v\f\"")) /* Need quotes.  */
    {
      p = stpcpy (p, "\"");
      for (s = string; *s; s++)
        {
          *p++ = *s;
          if (*s == '\"')
            *p++ = *s;
        }
      *p++ = '\"';
      *p = 0;
    }
  else /* Copy verbatim.  */
    p = stpcpy (p, string);

  return p;
}


/* Build a command line for use with W32's CreateProcess.  On success
   CMDLINE gets the address of a newly allocated string.  */
static int
build_w32_commandline (const char * const *argv,
		       int fd0, int fd0_isnull,
                       int fd1, int fd1_isnull,
                       int fd2, int fd2_isnull,
                       char **cmdline)
{
  int i, n;
  const char *s;
  char *buf, *p;
  char fdbuf[3*30];

  p = fdbuf;
  *p = 0;
  if (fd0)
    {
      if (fd0_isnull)
        strcpy (p, "-&S0=null ");
      else
        snprintf (p, 25, "-&S0=%d ", fd0);
      p += strlen (p);
    }
  if (fd1)
    {
      if (fd1_isnull)
        strcpy (p, "-&S1=null ");
      else
        snprintf (p, 25, "-&S1=%d ", fd1);
      p += strlen (p);
    }
  if (fd2)
    {
      if (fd2_isnull)
        strcpy (p, "-&S2=null ");
      else
        snprintf (p, 25, "-&S2=%d ", fd2);
      p += strlen (p);
    }
  
  *cmdline = NULL;
  n = strlen (fdbuf);
  for (i=0; (s = argv[i]); i++)
    {
      n += strlen (s) + 1 + 2;  /* (1 space, 2 quoting) */
      for (; *s; s++)
        if (*s == '\"')
          n++;  /* Need to double inner quotes.  */
    }
  n++;

  buf = p = xtrymalloc (n);
  if (! buf)
    return -1;

  p = stpcpy (p, fdbuf);
  for (i = 0; argv[i]; i++) 
    {
      *p++ = ' ';
      p = copy_quoted (p, argv[i]);
    }

  *cmdline = buf;
  return 0;
}


/* Create pipe where one end is inheritable: With an INHERIT_IDX of 0
   the read end is inheritable, with 1 the write end is inheritable.
   Note that the inheritable ends are rendezvous ids and no file
   descriptors or handles. */
static gpg_error_t
create_inheritable_pipe (int filedes[2], int inherit_idx)
{
  HANDLE hd;
  int rvid;

  filedes[0] = filedes[1] = -1;
  hd = _assuan_w32ce_prepare_pipe (&rvid, !inherit_idx);
  if (hd == INVALID_HANDLE_VALUE)
    {
      log_error ("_assuan_w32ce_prepare_pipe failed: %s\n", w32_strerror (-1));
      gpg_err_set_errno (EIO);
      return gpg_error_from_syserror ();
    }

  if (inherit_idx)
    {
      filedes[0] = handle_to_fd (hd);
      filedes[1] = rvid;
    }
  else
    {
      filedes[0] = rvid;
      filedes[1] = handle_to_fd (hd);
    }
  return 0;
}


/* Portable function to create a pipe.  Under Windows the write end is
   inheritable (i.e. an rendezvous id).  */
gpg_error_t
gnupg_create_inbound_pipe (int filedes[2])
{
  return create_inheritable_pipe (filedes, 1);
}


/* Portable function to create a pipe.  Under Windows the read end is
   inheritable (i.e. an rendezvous id).  */
gpg_error_t
gnupg_create_outbound_pipe (int filedes[2])
{
  return create_inheritable_pipe (filedes, 0);
}


static int
create_process (const char *pgmname, const char *cmdline,
                PROCESS_INFORMATION *pi)
{
  int res;
  wchar_t *wpgmname, *wcmdline;

  wpgmname = utf8_to_wchar (pgmname);
  if (!wpgmname)
    return 0;
  wcmdline = utf8_to_wchar (cmdline);
  if (!wcmdline)
    {
      xfree (wpgmname);
      return 0;
    }
  res = CreateProcess (wpgmname,      /* Program to start.  */
                       wcmdline,      /* Command line arguments.  */
                       NULL,          /* Process security attributes.  */
                       NULL,          /* Thread security attributes.  */
                       FALSE,          /* Inherit handles.  */
                       CREATE_SUSPENDED, /* Creation flags.  */
                       NULL,          /* Environment.  */
                       NULL,          /* Use current drive/directory.  */
                       NULL,          /* Startup information. */
                       pi);           /* Returns process information.  */
  xfree (wcmdline);
  xfree (wpgmname);
  return res;
}


/* Fork and exec the PGMNAME, see exechelp.h for details.  */
gpg_error_t
gnupg_spawn_process (const char *pgmname, const char *argv[],
                     estream_t infile, estream_t outfile,
                     void (*preexec)(void), unsigned int flags,
                     estream_t *statusfile, pid_t *pid)
{
  gpg_error_t err;
  PROCESS_INFORMATION pi = {NULL };
  char *cmdline;
  int inpipe[2], outpipe[2], errpipe[2];

  (void)preexec;
  (void)flags;
  
  /* Setup return values.  */
  *statusfile = NULL;
  *pid = (pid_t)(-1);

  /* A NULL INFILE or OUTFILE is only used by gpgtar thus we don't
     need to implement this for CE.  */
  if (!infile || !outfile)
    return gpg_error (GPG_ERR_NOT_IMPLEMENTED);

  es_fflush (infile);
  es_rewind (infile);

  /* Create a pipe to copy our infile to the stdin of the child
     process.  On success inpipe[1] is owned by the feeder.  */
  err = create_inheritable_pipe (inpipe, 0);
  if (err)
    {
      log_error (_("error creating a pipe: %s\n"), gpg_strerror (err));
      return err;
    }
  err = start_feeder (infile, inpipe[1], 1);
  if (err)
    {
      log_error (_("error spawning feeder: %s\n"), gpg_strerror (err));
      CloseHandle (fd_to_handle (inpipe[1]));
      return err;
    }

  /* Create a pipe to copy stdout of the child process to our
     outfile. On success outpipe[0] is owned by the feeded.  */
  err = create_inheritable_pipe (outpipe, 1);
  if (err)
    {
      log_error (_("error creating a pipe: %s\n"), gpg_strerror (err));
      return err;
    }
  err = start_feeder (outfile, outpipe[0], 0);
  if (err)
    {
      log_error (_("error spawning feeder: %s\n"), gpg_strerror (err));
      CloseHandle (fd_to_handle (outpipe[0]));
      return err;
    }


  /* Create a pipe for use with stderr of the child process.  */
  err = create_inheritable_pipe (errpipe, 1);
  if (err)
    {
      log_error (_("error creating a pipe: %s\n"), gpg_strerror (err));
      return err;
    }

  /* Build the command line.  */
  err = build_w32_commandline (argv,
                               inpipe[0], 0,
                               outpipe[1], 0,
                               errpipe[1], 0,
                               &cmdline);
  if (err)
    {
      CloseHandle (fd_to_handle (errpipe[0]));
      return err; 
    }

  
  log_debug ("CreateProcess, path=`%s' cmdline=`%s'\n", pgmname, cmdline);
  if (!create_process (pgmname, cmdline, &pi))
    {
      log_error ("CreateProcess failed: %s\n", w32_strerror (-1));
      xfree (cmdline);
      CloseHandle (fd_to_handle (errpipe[0]));
      return gpg_error (GPG_ERR_GENERAL);
    }
  xfree (cmdline);
  cmdline = NULL;

  /* Note: The other end of the pipe is a rendezvous id and thus there
     is no need to close.  */

  log_debug ("CreateProcess ready: hProcess=%p hThread=%p"
             " dwProcessID=%d dwThreadId=%d\n",
             pi.hProcess, pi.hThread,
             (int) pi.dwProcessId, (int) pi.dwThreadId);
  

  /* Process has been created suspended; resume it now. */
  ResumeThread (pi.hThread);
  CloseHandle (pi.hThread); 

  *statusfile = es_fdopen (handle_to_fd (errpipe[0]), "r");
  if (!*statusfile)
    {
      err = gpg_error_from_syserror ();
      log_error (_("can't fdopen pipe for reading: %s\n"), gpg_strerror (err));
      CloseHandle (pi.hProcess);
      return err;
    }

  *pid = handle_to_pid (pi.hProcess);
  return 0;

}



/* Simplified version of gnupg_spawn_process.  This function forks and
   then execs PGMNAME, while connecting INFD to stdin, OUTFD to stdout
   and ERRFD to stderr (any of them may be -1 to connect them to
   /dev/null).  The arguments for the process are expected in the NULL
   terminated array ARGV.  The program name itself should not be
   included there.  Calling gnupg_wait_process is required.

   Returns 0 on success or an error code. */
gpg_error_t
gnupg_spawn_process_fd (const char *pgmname, const char *argv[],
                        int infd, int outfd, int errfd, pid_t *pid)
{
  gpg_error_t err;
  PROCESS_INFORMATION pi = {NULL};
  char *cmdline;

  /* Setup return values.  */
  *pid = (pid_t)(-1);

  if (infd != -1 || outfd != -1 || errfd != -1)
    return gpg_error (GPG_ERR_NOT_SUPPORTED);

  /* Build the command line.  */
  err = build_w32_commandline (argv, -1, 1, -1, 1, -1, 1, &cmdline);
  if (err)
    return err; 

  log_debug ("CreateProcess, path=`%s' cmdline=`%s'\n", pgmname, cmdline);
  if (!create_process (pgmname, cmdline, &pi))
    {
      log_error ("CreateProcess(fd) failed: %s\n", w32_strerror (-1));
      xfree (cmdline);
      return gpg_error (GPG_ERR_GENERAL);
    }
  xfree (cmdline);
  cmdline = NULL;

  log_debug ("CreateProcess(fd) ready: hProcess=%p hThread=%p"
             " dwProcessID=%d dwThreadId=%d\n",
             pi.hProcess, pi.hThread,
             (int) pi.dwProcessId, (int) pi.dwThreadId);
  
  /* Process has been created suspended; resume it now. */
  ResumeThread (pi.hThread);
  CloseHandle (pi.hThread); 

  *pid = handle_to_pid (pi.hProcess);
  return 0;
}


/* See exechelp.h for a description.  */
gpg_error_t
gnupg_wait_process (const char *pgmname, pid_t pid, int hang, int *exitcode)
{
  gpg_err_code_t ec;
  HANDLE proc = fd_to_handle (pid);
  int code;
  DWORD exc;

  if (exitcode)
    *exitcode = -1;

  if (pid == (pid_t)(-1))
    return gpg_error (GPG_ERR_INV_VALUE);

  /* FIXME: We should do a pth_waitpid here.  However this has not yet
     been implemented.  A special W32 pth system call would even be
     better.  */
  code = WaitForSingleObject (proc, hang? INFINITE : 0);
  switch (code) 
    {
    case WAIT_TIMEOUT:
      ec = GPG_ERR_TIMEOUT;
      break;
      
    case WAIT_FAILED:
      log_error (_("waiting for process %d to terminate failed: %s\n"),
                 (int)pid, w32_strerror (-1));
      ec = GPG_ERR_GENERAL;
      break;

    case WAIT_OBJECT_0:
      if (!GetExitCodeProcess (proc, &exc))
        {
          log_error (_("error getting exit code of process %d: %s\n"),
                     (int)pid, w32_strerror (-1) );
          ec = GPG_ERR_GENERAL;
          }
      else if (exc)
        {
          log_error (_("error running `%s': exit status %d\n"),
                       pgmname, (int)exc );
          if (exitcode)
            *exitcode = (int)exc;
          ec = GPG_ERR_GENERAL;
        }
      else
        {
          if (exitcode)
            *exitcode = 0;
          ec = 0;
        }
      break;
      
    default:
      log_error ("WaitForSingleObject returned unexpected "
                 "code %d for pid %d\n", code, (int)pid );
      ec = GPG_ERR_GENERAL;
      break;
    }

  return gpg_err_make (GPG_ERR_SOURCE_DEFAULT, ec);
}


void
gnupg_release_process (pid_t pid)
{
  if (pid != (pid_t)INVALID_HANDLE_VALUE)
    {
      HANDLE process = (HANDLE)pid;
      
      CloseHandle (process);
    }
}


/* Spawn a new process and immediatley detach from it.  The name of
   the program to exec is PGMNAME and its arguments are in ARGV (the
   programname is automatically passed as first argument).
   Environment strings in ENVP are set.  An error is returned if
   pgmname is not executable; to make this work it is necessary to
   provide an absolute file name.  All standard file descriptors are
   connected to /dev/null. */
gpg_error_t
gnupg_spawn_process_detached (const char *pgmname, const char *argv[],
                              const char *envp[] )
{
  gpg_error_t err;
  char *cmdline;
  PROCESS_INFORMATION pi = {NULL };

  (void)envp;
  
  /* Build the command line.  */
  err = build_w32_commandline (argv, -1, 1, -1, 1, -1, 1, &cmdline);
  if (err)
    return err; 

  /* Note: There is no detached flag under CE.  */
  log_debug ("CreateProcess, path=`%s' cmdline=`%s'\n", pgmname, cmdline);
  if (!create_process (pgmname, cmdline, &pi))
    {
      log_error ("CreateProcess(detached) failed: %s\n", w32_strerror (-1));
      xfree (cmdline);
      return gpg_error (GPG_ERR_GENERAL);
    }
  xfree (cmdline);
  cmdline = NULL;

  log_debug ("CreateProcess(detached) ready: hProcess=%p hThread=%p"
             " dwProcessID=%d dwThreadId=%d\n",
             pi.hProcess, pi.hThread,
             (int) pi.dwProcessId, (int) pi.dwThreadId);
  
  /* Process has been created suspended; resume it now. */
  ResumeThread (pi.hThread);
  CloseHandle (pi.hThread); 

  return 0;
}


/* Kill a process; that is send an appropriate signal to the process.
   gnupg_wait_process must be called to actually remove the process
   from the system.  An invalid PID is ignored.  */
void
gnupg_kill_process (pid_t pid)
{
  if (pid != (pid_t) INVALID_HANDLE_VALUE)
    {
      HANDLE process = (HANDLE) pid;
      
      /* Arbitrary error code.  */
      TerminateProcess (process, 1);
    }
}